(CNN) -- British police were told in March this year that missing girl Madeleine McCann may have been kidnapped by a pedophile ring which followed her three days before her abduction, according to reports.

Madeleine McCann went missing in May 2007 after being left at a holiday apartment in the Algarve region.

Britain's Daily Telegraph and The Sun newspapers both reported Thursday that an email released this week as part of the documents compiled by the Portuguese investigators probing Madeleine's disappearance revealed the connection to the ring.

Madeleine was 3 when she disappeared May 3, 2007, while she was on holiday with her family at the Portuguese resort of Praia da Luz. Her disappearance prompted headlines worldwide.

According to the newspapers, the email was sent on March 4 by a London-based Metropolitan Police intelligence officer to Leicestershire police -- Madeleine's home county -- who then forwarded it on to investigators in Portugal more than a month later.

In the email, which both newspapers printed a copy of, the officer writes that "intelligence suggests that a pedophile ring in Belgium made an order for a young girl three days before Madeleine McCann was taken.

"Somebody connected to this group saw Maddie, took a photograph of her and sent it to Belgium. The purchaser agreed the girl was suitable and Maddie was taken," the officer wrote.

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The case files, released by the Portuguese investigators this week after they shelved the investigation for lack of evidence last month, have provided a raft of leads for the media to report.

On Tuesday, the documents revealed a previously undisclosed sighting of Madeleine in the Netherlands shortly after her disappearance.

The possible sighting of Madeleine in May 2007 stemmed from a report by a Dutch shopkeeper, who told authorities she encountered a little girl in Amsterdam, the Netherlands.

She said the child identified herself as Maddie and said she was taken from her mother while on holiday.

"I start to ask where her mommy was," Anna Stam said. "She couldn't tell me that. I wanted to give her a balloon, but she didn't want that. She only wants her mommy, she said. And she said that these people took her from her mommy."

At one point, authorities had named the girl's parents, Kate and Gerry McCann, as "arguidos," or suspects, along with a British man living in Portugal, Robert Murat. But a spokesman for the Portuguese public prosecutor's office said authorities found no evidence of involvement by any of the three and were no longer considering them "arguidos."

After closing the case, police turned their case file -- containing up to 30,000 pages -- over to attorneys and private investigators working for the McCanns.